Relationship between polyamine accumulation and RNA biosynthesis and content during the cell cycle

Summary Polyamine accumulation was related to RNA biosynthesis and content during the cell cycle of CHO-K1 and HeLa cells. The highest correlations were observed between polyamine accumulation and RNA content. Feeding, serumstarved cultures of embryonic chick fibroblasts, which exhibit a 3-fold increase in RNA content, demonstrated that RNA content was most closely paralleled by spermidine content.I acknowledge the receipt of a Medical Research Council studentship.     

Action de la ribonucléase sur les cellules du carcinome d'Ehrlich

Summary The reduced form of ribonuclease acts on the cells ofEhrlich's carcinoma by producing important changes in the RNA content of cells:(1) First, there is an important synthesis of intracellular RNA and an accumulation of free nucleotides (from the external medium). This phenomenon accompanies the necrosis of the cells.(2) After this first stage begins a rapid degradation of intracellular RNA.Simultaneously, the respiration of cells decreases whilst protein content remains unchanged.The oxidized form of ribonuclease has no action on the cells.

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Aspirant du Fonds national belge de la Recherche scientifique.     

Growth metabolism of diaphragm in Swiss albino mice

Summary During the postnatal growth of diaphragm in swiss albino mice, a continuous decline in glycogen content reciprocates with the increasing SDH-activity and protein accumulation. An inverse relationship between DNA-contents and the basic protein levels points towards the regulatory behaviour of the latter during protein synthesis. While the variations in the contents of DNA and RNA speak of a feedback mechanism operative between the 2 nucleic acids during the postnatal growth, the fluctuations in RNA appear to be significant in determining the amount of acidic proteins, in this muscle.     

Growth metabolism of diaphragm in Swiss albino mice

During the postnatal growth of diaphragm in swiss albino mice, a continuous decline in glycogen content reciprocates with the increasing SDH-activity and protein accumulation. An inverse relationship between DNA-contents and the basic protein levels points towards the regulatory behaviour of the latter during protein synthesis. While the variations in the contents of DNA and RNA speak of a feedback mechanism operative between the 2 nucleic acids during the postnatal growth, the fluctuations in RNA appear to be significant in determining the amount of acidic proteins, in this muscle.     

Poly(A) associated RNA from mitochondria and microsomes of rat brain

Summary Rat brain mitochondria contain a significant proportion of poly(A) associated RNA which is higher than that found in microsomes from the same source. When steady state poly(A) RNA of brain mitochondria was analyzed by microelectrophoresis, it displayed a characteristic separation pattern with a large amount of free poly(A).     

Primary nucleolus and amphinucleoli in the oocytes ofPatella coerulea L. (Moll. Gast.)

Summary Electron microscope observations show in the primary nucleolus some granulations with dimensions less (70 Å) than those of the amphinucleoli (90 Å). Even though the primary nucleolus has a high RNA content, this has not a very active turnover except at the periphery, probably in relation to the emission of daughter-nucleoli. The amphinucleoli, even though they do not have RNA which is cytochemically discloseable, possess, however, RNA at a very high rate of turnover.     

Estrogen and accessory sex gland lipids

Summary Administration of estradiol-17 elicited differential responses on accessory sex glands of rats. In caput epididymis, the estrogen treatment led to an accumulation of glycerides and phospholipids while in cauda epididymis, there was no significant change. However, in seminal vesicles, depletion of phospholipids was observed In prostate, the treatment, resulted in an accumulation of glycerides.Part of Ph.D. Thesis. Umapathy, E., Thesis. University of Madras, India, 1977.     

High salt effect on RNA synthesis in Krebs ascites tumor cells

Summary The incubation of Krebs ascites tumor cells in medium with a high salt concentration resulted in a partial inhibition of nuclear RNA synthesis. The residual RNA polymerase activity in such nuclei was only slightly inhibited by low concentrations (50 nM) of -amanitin. This finding suggested an inhibition of RNA polymerase II activity under conditions of medium hypertonicity. Indeed, RNA polymerase II, isolated from the nuclei of cells exposed to hypertonicity, revealed only half of the control activity. On the other hand, RNA polymerase I was not affected by hypertonicity. Moreover, chromatin fractions isolated from cells incubated in hypertonic or isotonic medium were equally template-active in RNA synthesis.This investigation was supported by the Turkish Scientific and Technical Research Council (TÜBITAK), Project No. TAG 339.     

Die Veränderung des Stärke-, Protein- und RNS-Gehaltes vonLemna minor L. unter dem Einfluss von Kinetin (6-Furfurylaminopurin)

Summary Kinetin (6-furfurylaminopurine) is rapidly absorbed byLemna minor L. 3 · 10^–8 M/ml medium cause an immediate but temporary stimulation of RNA and protein synthesis during the first hour of the treatment. The following excessive accumulation of starch is considered to be more or less a direct consequence of a disturbed RNA and protein metabolism.     

Transient cytoskeletal alterations after SOD1 depletion in neuroblastoma cells

We have studied the effects of superoxide production after Cu,Zn superoxide dismutase (SOD1) down-regulation by RNA interference. We demonstrated that SOD1 depletion induced, only in neuroblastoma cells, a decrease in actin and β-tubulin content and accumulation of neurofilament light chain and Tau proteins. Alterations of cell morphology and the microfilament network were also observed, together with the up-regulation of the Cdk5/p35 pathway, which is involved in the regulation of actin polymerization. The decrease of filamentous actin was transient and was recovered through the activation of p38/Hsp27 MAPK pathway, as well as after treatment with N-acetyl-L-cysteine. The importance of p38 in the recovery of cytoskeleton was confirmed by experiments carried out in the presence of its inhibitor SB203580, which induced cell death. Our data demonstrate that SOD1 is essential for the preservation of cytoskeleton integrity, by maintaining physiological concentration of reactive oxygen species and inhibiting the activation of the neuronal specific Cdk5/p35 pathway. P. Vigilanza, K. Aquilano: Both authors equally contributed to this work. Received 15 November 2007; received after revision 19 January 2008; accepted 22 January 2008     

Cytochemical evidence for stage-specific changes of nuclear RNA and nonhistone protein content during early development ofTriturus vulgaris

Summary During early embryogenesis ofTriturus vulgaris, RNA and nonhistone protein contents of neuroectoderm nuclei change with stage specifically. Maximum values were found in the late gastrula after embryonic induction, and in the late neurula with the formation of the neural tube. The stage-specific increases of RNA and nonhistone protein are correlated with a preceding increase of Feulgen-DNA content.     

Adrenocortical metabolism and plasma corticosterone in soman intoxicated rabbits

Summary The organophosphate neurotoxin soman produced impairments in adrenocortical RNA and protein metabolism. Fasciculate and reticular cell RNA and protein contents were supporessed with sublethal to acutely lethal dosages (20, 30 and 40 g/kg, s.c.) during the acute excitatory phase of intoxication and at 6–8 h post injection. All three dosages produced ca 90% inactivation of plasma cholinesterase. A transient elevation of plasma corticosterone occurred with 20 g/kg soman whereas there was a protracted increase with 30 g/kg. Corticosterone was not significantly elevated with 40 g/kg, but death occurred at 13±4 min. Thus, the magnitude and/or nature of soman-induced metabolic impairments does not appear to prevent adrenal activation.Supported by US Army Medical Research and Development Command Contract DAMD 17-81-C-1202.     

K-p-nitrophenylphosphatase activity, Na and K content, Na permeability and membrane lipid composition in rabbit myocardium after cholesterol rich diet

The aim of the present study was to investigate the effects of a cholesterol-rich diet on membrane function and lipid composition in rabbit myocardium. The activity and the ouabain sensitivity of the K-p-nitrophenylphosphatase (K-pNPPase), a partial reaction of the Na, K-ATPase, were diminished after a cholesterol/oil or pure cholesterol diet. The content of cholesterol, cholesterol esters and of several classes of phospholipids was enhanced in microsomes. A causal relationship is assumed between cholesterol accumulation and a decrease in membrane fluidity as well as in Na, K-ATPase activity. The intracellular Na content and the Na-Li-exchange rate were higher after the cholesterol diet. The increase in the Na content is supposed to be induced by a lower Na transport and a higher Na permeability. An enhanced Ca flux via the sarcolemma could be the consequence.     

Unchanged r-RNA-gene dose in mice liver cells of different developmental stages.

The content of ribosomal DNA in mice liver at the beginning as well as near the end of the hematopoietic period was measured by RNA/DAN-hybridization in solution. At both stages the amount of ribosomal DNA was the same and comparable to that of postnatal liver.     

Aptamer and its applications in neurodegenerative diseases

Aptamers are small single-stranded DNA or RNA oligonucleotide fragments or small peptides, which can bind to targets by high affinity and specificity. Because aptamers are specific, non-immunogenic and non-toxic, they are ideal materials for clinical applications. Neurodegenerative disorders are ravaging the lives of patients. Even though the mechanism of these diseases is still elusive, they are mainly characterized by the accumulation of misfolded proteins in the central nervous system. So it is essential to develop potential measures to slow down or prevent the onset of these diseases. With the advancements of the technologies, aptamers have opened up new areas in this research field. Aptamers could bind with these related target proteins to interrupt their accumulation, subsequently blocking or preventing the process of neurodegenerative diseases. This review presents recent advances in the aptamer generation and its merits and limitations, with emphasis on its applications in neurodegenerative diseases including Alzheimer’s disease, Parkinson’s disease, transmissible spongiform encephalopathy, Huntington’s disease and multiple sclerosis.     

The mode of action of bacteriocin N5 purified from Clostridium perfringens]

The purified bacteriocin N5 produced by Clostridium perfringens BP6K inhibited simultaneously the syntheses of DNA, RNA and protein in sensitive cells, without DNA degradation. Bacteriocin N5 inhibited the accumulation of leucin and caused the exit of the previously accumulated amino acid. The effects of bacteriocin N5 are very similar to those observed for colicins E1, K, A and I.     

High poly A content of the native genome of murine oncornaviruses : presence of 65-70 S RNA lacking polyadenylic sequences]

High molecular weight Poly (A) minus RNA was isolated from native genome of murine oncornaviruses. The Poly (A) content of viral genomes seems to depend more on cellular multiplication than viral maturation.     

Dissociation of separate mechanisms of estrogen action by actinomycin D

Summary Pretreatment with actinomycin D 1 h before estrogen administration completely blocks estrogen-induced increases in uterine RNA and protein content, but does not counteract estrogen-induced uterine eosinophilia, edema and increase in glycogen content.Acknowledgments. This work was supported by the Belgian Ministry of Scientific Policy (Concerted Actions of Research) and by the Servicio de Desarrollo Cientifico, Artistico y de Cooperacion Internacional from the University of Chile.